This disclosure generally relates to an auxiliary power unit. More particularly, this disclosure relates to an auxiliary power unit that includes a gas generator that drives an electric generator through a free power turbine.
Aircraft typically utilize an auxiliary power unit to provide electrical power to various systems when the main propulsion engines are not running. An auxiliary power unit typically includes a gas turbine engine that drives a generator through a gear train assembly. The gear train assembly is required as the optimal speed of the gas turbine engine is typically different than the optimal speed of the generator.